The question is not how to become a buddhist; the aim is to get freed from our misery (dukkha). This is possible through realizing wisdom (panna).
Everyone can become enlightened. The Buddha has given us the tools; showed us the path, but everyone has to cultivate it himself or herself.
Ajahn Jayasaro (* Mindfulness, Precepts and Crashing in the Same Car p. 33-35 emphasized text*):
'The Buddha says we can find an inner refuge in which we become like
an island unto ourselves, like a mountain which is unmoved by wind and
rain and weather. This kind of stability and integrity of mind 'is not
found by turning our backs on certain experiences and trying to create
some special blissed-out state. If you practice meditation because
you’re fed up with life, or you’re fed up with yourself, and you just
want to go somewhere else where you don’t have to put up with all this
stuff, then you’re already on the wrong path. That is the practice
that may lead to heaven. But it’s not the practice for liberation.
You might be able to enter some heavenly realm where you can just
close your eyes and feel good for a while, but the ability to do that
is conditioned by health, by external circumstances and so on, and
it’s not something we can ultimately rely upon. The immediate
understanding of things as they are, of highs as highs, lows as lows,
thoughts as thoughts, perceptions as perceptions, this is where the
stability comes. We begin to see things less as solid entities, we
perceive less in terms of personalities and people, and more and more
in terms of a stream, a conditioned flow of phenomena.'